‘We’re in the bullseye’ of storm

MILLIONS of Americans are preparing for what could become one of the most catastrophic hurricanes to hit the eastern seaboard in decades, with Florence on the brink of a Category 5 and barrelling towards the US East Coast.

Mandatory evacuations have begun in three states, with more than 1.5 million ordered to leave their homes as Hurricane Florence, packing winds of 220km/h, is expected to grow even stronger before making landfall on Thursday.

The monster storm was upgraded to an "extremely dangerous" Category 4 by the National Hurricane Centre yesterday but is predicted to approach the most-damaging Category 5 status. The storm's most likely landfall will be between northern South Carolina and North Carolina's Outer Banks on Thursday.

If maps of Florence's trajectory are correct, it will become the most powerful storm to strike the Carolinas in nearly three decades.

In case you're wondering what a category 4 storm surge looks like along the South Carolina coast. This was Garden CIty after Hugo in 1989. GC is 50 miles north of where Hugo made landfall. The storm surge was 14 feet. #scwx#ncwx#Florencepic.twitter.com/t1nX55ekh0

Authorities are warning about Florence's potential to unleash prolonged torrential rains and life-threatening floods, down trees, knock out electricity and submerge entire communities - especially if it slows to a crawl and lingers inland for several days, just as Hurricane Harvey stalled over Texas in 2017.

"This is one of the worst storms to hit the East Coast in many years," US President Donald Trump tweeted Monday evening. "Please be prepared, be careful and be SAFE!"

To the incredible citizens of North Carolina, South Carolina and the entire East Coast - the storm looks very bad! Please take all necessary precautions. We have already began mobilizing our assets to respond accordingly, and we are here for you! pic.twitter.com/g74cyD6b6K

At least 250,000 more people were due to be evacuated from the northern Outer Banks in North Carolina on Tuesday after more than 50,000 people were ordered on Monday to leave Hatteras and Ocracoke, the southernmost of the state's barrier islands.

North Carolina, South Carolina, Virginia and Maryland governors have declared states of emergency.

The storm's potential path includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous hog farms that store animal waste in massive open-air lagoons. The very centre of Florence's bullseye may be Camp Lejeune, the sprawling Marine Corps training base.

"This is going to produce heavy rainfall, and it may not move very fast. The threat will be inland, so I'm afraid, based on my experience at FEMA, that the public is probably not as prepared as everybody would like," said Craig Fugate, former director of the Federal Emergency Management Agency.

Impacts of Florence are likely to begin tomorrow.

It is feared Florence could hit the Carolinas harder than any hurricane since Hurricane Hazel packed 209km/h winds in 1954. That Category 4 storm destroyed 15,000 buildings and killed 19 people in North Carolina. In the six decades since then, many thousands of people have moved to the coast.

- with wires

FILE-In this Oct. 15, 1954 file photo, Hurricane Hazel destruction is seen in Morehead City, North Carolina, back in 1954. Picture: Clifton Guthrie